Yyyyup.
Take into account that armor itself is the only source of permanent-enchant AC bonus in 4e, and I'm thinking that 4e AC is now plotted out as a balancing factor by armor type. Defenders, who need high AC, wear heavy armor. Strikers and leaders, who wade into melee to varying degrees, wear light to medium armor. And wizards (and possibly some strikers, like warlocks) wear cloth armor.
I'm thinking that if you want to play a light-armored melee warrior, ranger and/or rogue might be a better approach than fighter in 4e. Remember, those two carved up the swashbuckler and took his stuff.
I have a bit of trouble deciding how I feel about this. On the one hand, it seems weird to say, "My character carves through enemies with an axe in each hand. Clearly Ranger is the class for him!" But on the other hand, it makes sense that they'd want to parse out the martial-defender from the martial-striker, and the fast-and-dodgy fighter builds are definitely more "striker" than "defender."